-LRB- CNN -RRB- -- A politically active Marine who has questioned President Barack Obama 's authority said Thursday that he is facing administrative discharge proceedings over his comments .

Sgt. Gary Stein , who founded the Armed Forces Tea Party , said his commanding officer at Camp Pendleton near San Diego has accused him of violating a catch-all military justice provision against conduct endangering `` good order and discipline . ''

He is also accused of violating a Department of Defense policy limiting the political activities of service members .

Stein came under scrutiny from Marine officials after saying he would not obey Obama 's orders .

In a January 26 post to the Armed Forces Tea Party Facebook page , Stein called Obama a liar . Two days later , he said the president is `` the ` Domestic Enemy ' our oath speaks about . ''

In a March 4 posting , he questioned Obama 's birth certificate . Another discussion on the site in March said he would refuse to obey orders given by Obama . He later clarified to say he meant illegal orders , which he has explained as orders such as sending the military to Syria without congressional approval .

`` The allegations drummed up against me are no more than an agenda by the Marine Corps to use me as an example , '' Stein said in a statement posted to his page . `` If I am guilty of anything it would be that I am American , a freedom loving Conservative , hell bent on defending the constitution and preserving Americas greatness . ''

He noted that the opinions he expressed were his own , saying , `` I have never spoken on behalf of the Marine Corps or in uniform . ''

Appearing on CNN on Thursday morning , he called the charges a `` PR thing . ''

`` They have to make some sort of stand with this , '' he said .

A Marine Corps spokesman confirmed Thursday that Stein 's commanding officer had chosen to address the allegations through `` administration action '' after he had received the results of a preliminary inquiry into the case .

While the First Amendment to the U.S. Constitution protects the free speech rights of ordinary citizens , a Defense Department rule prohibits service members from engaging in some forms of political activity .

Among the prohibited activities are publishing partisan political articles or serving in an official capacity with a partisan political club .

Stein has said that has carefully followed the Defense Department directive . He said Thursday that his unit has known about his off-duty activities since he joined the outfit eight months ago .

He also said a similar investigation two years ago found that he had done nothing wrong and officers at the time told him he could continue running the site so long as it carried a disclaimer .

The Facebook page notes that it does not represent and is not affiliated with the military or government .

About 18,000 people follow posts on the page .

Comments Tuesday on the page were largely , but not entirely , supportive of Stein .

`` Gary Stein I stand behind you 100 % . Keep up the good fight , '' one poster commented .

`` Like it or not Obama is the Commander in Chief and this Marines job is to protect him Right or wrong , '' another poster said .

Stein is not the first service member to face controversy over comments about Obama .

In 2010 , a military court sentenced Army Lt. Col. Terrence Lakin to six months in prison and removal from the military over his refusal to deploy to Afghanistan .

Lakin argued that Obama was not born in the United States and therefore was not legally president , making his orders illegal .

CNN 's Adam Levine contributed to this report .

@highlight

A Marine who criticized Obama is facing administrative discharge proceedings

@highlight

Sgt. Gary Stein says he 's accused of violating `` good order and discipline ''

@highlight

He 's also accused of violating a Defense Department rule against some political activity

@highlight

He calls the allegations a `` PR thing ''